Molecular diagnostics includes the analysis of single biomolecules, which are faster, weaker, and more stochastic than their macroscale counterparts. Consequently, single-molecule measurements are regularly constrained by poor signal-to-noise ratios, and temporal resolution is commonly sacrificed in exchange for lower noise amplitudes. Optical and mechanical nanosensors may operate near their intrinsic noise floors, but electronic platforms often plateau at limits jointly determined by the sensors together with their electronic acquisition circuits.
Acquisition circuitry based on high-value pseudo-resistors, timed integrators with an external frequency reference, switched-capacitor networks and logarithmic feedback elements face difficult tradeoffs between bandwidth, noise, and dynamic range. Although resistive transimpedance amplifiers have a straightforward implementation, they have relatively low performance. Discrete-time systems have higher performance but lower bandwidth. Logarithmic systems offer wide dynamic range but are limited by poor linearity and temperature dependence.